With Microsoft officially ending support for Windows XP as of 2 days ago, it's going to be harder and harder to justify keeping any system of any value, with any useful data on it, on that OS at this point. It's just going to get uglier and uglier over the next few months. That said, there are still a reasonable number of users on XP that I hope can get to SP3 if they aren't upgrading to 7 or 8 in the near term. It looks like roughly 5% of ninjette.org users here in the past 30 days are using XP. (these totals aren't page views, they are visits, which groups all related page views as one visit)
OS in general
Windows OS - split by version reported